The present invention generally relates to vehicle brake systems and more particularly relates to a hydraulic unit for a hydraulic control and/or regulating device for anti-lock and/or anti-slipping brake systems.
DE 42 34 013 A1 discloses a hydraulic unit of the type described above. The most recent hydraulic units have a modular design and essentially comprise such hydraulic components as pump, low-pressure accumulator, solenoid valves and a driving means for the pump. Integrated coils arranged in the electronic control housing are attached directly to the solenoid valves and fastened to the valve block. For this purpose, an eccentric driven by the drive shaft of a driving means is provided in the valve block, and it actuates the pressure-generating elements. The pressure-generating elements are sealed off against the cavity of the eccentric by means of elastic seals; however, leakages cannot always be avoided at pressure levels up to 250 bar. Therefore, a discharge channel is provided in the valve block, so that the leakage fluid of the pressure-generating elements can flow off. The leakage fluid flows through the discharge channel to the outer wall of the valve block, to which the control housing is fastened. Now the hydraulic unit should be installed in such locations and positions that the specifications regarding the operativeness of the brake system, for example a splash-water test, can be met. However, due to the complex arrangement of units in the complete motor vehicle and the high integration density of the systems in the motor vehicle, this cannot always be fulfilled. Salt or water entering into the valve, pump, engine and pressure accumulator spaces collects in the cavities and, in some cases, may lead to overflowing. Malfunctions cannot be completely eliminated. Special measures, which generally render the unit more expensive, are necessary to ensure operativeness.
In order to counteract these circumstances, the control housing commonly is sealed off against the valve block by means of a seal which is fixed in place in a recess in the controller wall in a usual manner.
Consequently, this leads to a sealed surface extending over the entire valve block, the operativeness of which can only be ensured with great difficulty. Furthermore, such a unit has to be ventilated and deaerated, which increases the unit""s cost.
Hence, the object of the present invention is to disclose a hydraulic unit that safely prevents a fluid from entering into the discharge channel and, at the same time, allows the leakage fluid to flow off from the discharge channel and the control housing.
Hence, this invention is based on the concept of connecting the valve block and control housing without any seal in-between, so as to fasten the control housing to the valve block in a simpler and less expensive manner, and to this end a means arranged within the housing space and associated with the discharge channel for preventing the leakage fluid prevents a fluid, e.g. water, from entering into the discharge channel.
The present invention includes a protective element that at least partially surrounds the discharge opening and diverts the fluid from the discharge opening. This gives rise to two particularly simple ways of producing the necessary means. One particularly reliable, easy-to-install and low-cost solution to the existing problem is described herein. In this case, the leakage fluid preventing means is connected in one piece to the control housing made of a plastic material. The roof-like means, under pretension, is moved into abutment with the wall of the valve block in the direction of infiltration of the fluid upstream of the outlet of the discharge channel and guides the fluid into the control housing. In this configuration, the means can be formed by means of injection moulding during production of the control housing.
In an alternative configuration of the leakage fluid preventing means, wherein this means is connected separably to the valve block. Preferably, the means is pipe-shaped and connects the discharge channel to an interior space of the control housing in which the coils of the brake system are arranged. The pipe-shaped means carries out two functions: it guides the leakage fluid to the interior space of the control housing and prevents infiltration of fluid, since the outlet of the pipe-shaped means is located inside the control housing and the fluid flows between control housing and valve block.
Whenever necessary, the discharge channel can be connected to a reservoir via the leakage fluid preventing means, whereby leakage fluid can be collected in the reservoir. For this purpose, an absorbent medium, whose surface does not allow infiltration of fluid with low viscosity, can be used for absorbing the fluid.
These measures take into consideration the daily requirements arising later during operation, since the leakage fluid is not discharged through the engine chamber of a motor vehicle, which could be misinterpreted by the user of the motor vehicle.
A particularly simple way of installing and removing the leakage fluid preventing means is disclosed wherein the means is positioned in the discharge channel. This can be implemented particularly easily and at low cost in the pipe-shaped configuration, provided the diameter of the means corresponds to the diameter of the discharge channel. This is particularly cost-efficient when a plastic pipe that can be inserted in the discharge channel is used.
Also disclosed in the present invention is a means equipped with a valve safely prevents infiltration of a fluid if necessary. It would be appropriate to provide drip-off edges on the means, so that the fluid can be discharged at a specified position. Consequently, a defined flow of fluid can be ensured. When a section of the means extends at an angle, the leakage fluid can be discharged precisely to a defined position within the control housing and infiltration of a fluid corresponding to the position of installation of the hydraulic unit is definitely prevented. In an advantageous embodiment a control housing of the type described above exhibits means connected to it in one piece, which prevents fluid from entering into the discharge channel of a valve block. A means for the discharge channel of a hydraulic unit, which is pipe-shaped, can be advantageously produced as a separate single part and assembled as a purchased part.
Other objectives, characteristics, advantages and application possibilities of the present invention are stated in the following descriptions of embodiments. In this connection, all described and/or illustrated characteristics form the object of the invention either by themselves or in any meaningful combination, irrespective of how they are combined in the claims or appendencies.